This application is a continuation application of U.S. Ser. No. 10/403,952, filed Mar. 31, 2003, now abandoned.
Engine mounts are generally well known in the industry and typically employ a combination of elastomeric and/or hydraulic features that provide effective vibration isolation. The performance of the mount is directly connected to the volume of rubber and the clearance around it. Both are required for optimal isolation and rough load powertrain handling. The space constraints also must address the need for access tool clearance and assembly process feasibility.
Moreover, there are various constraints imposed in this environment. For example, space or packaging is a primary concern as designs are required to deliver the same performance in smaller dimensional constraints. High temperature exposure is another constraint. For example, the mount design must be capable of withstanding an excursion temperature on the order of 175° C. Another constraint relates to high load conditions, especially for truck applications, where the mount must be capable of handling peak loads on the order of 10G. Still another constraint is the ability to provide a mount that can be easily tuned and preferably one that uses many of the same mount components, including a modular type of design that allows components or a subassembly to be added or removed as an option, resulting in ease of manufacture in developing different stiffnesses and force/displacement relationships as desired.
Tradeoffs between these constraints have tended to limit the various mount designs brought to the marketplace. For example, packaging space tends to discourage use of a heavy metal bracket, or sophisticated design driven by the hydraulic technology; however, part durability must be carefully considered if a heavy metal bracket is not used. A tradeoff also exists between developing the proper rubber geometry that provides the desired stiffness and durable rubber deformed shape required for a typical truck mount load, and at the same time designing the fluid related components of the mount in order to establish the requisite fluid effect that produces the high level of damping needed in, for example, truck applications.
U.S. Pat. No. 6,499,729 provides a concise discussion of ways in which the industry has addressed the need for a stiffer sealing/crimping area. These current applications are loading through the crimp region or crimp area of the mount, that is, the mount is directly supported or mounted through the cover. Since the cover is intended to carry the load, an increased emphasis is required on the sealing or crimping area in order to maintain a hydraulic or fluid-tight seal between the chamber and a reservoir. Thus, attention is directed to enhancing the perimeter or edge portion of the seal where the load transfer through the mount cover interfaces with the diaphragm/bellows arrangement.
It is also desirable to maximize the length of the track path on the inertia track of a hydromount. Maximizing the track path length provides sufficient fluid effect to produce a high level of damping required in extreme load conditions such as encountered with a truck application. The inertia space and the need for high fluid damping have not been adequately addressed in the prior art.
Because of the need to transfer forces or extreme loads through the mount, use of alternative materials of construction has been limited. Extreme loads typically require the mount structure to be at least partially, if not entirely, formed of metal to withstand extreme loads. For example, typical hydromounts use the inertia track as a travel limiter or a structural reinforcement in order to stop powertrain motion in compression and likewise reach higher modal frequencies. Therefore, it is conventional to form the inertia track from metal.
Still another problem encountered with prior arrangements is that the mount is usually secured to a vehicle flange along a large planar area. It has been determined that the planar interface is another potential area of rattling or secondary resonation.